Kynurenine aminotransferase activity in human liver: identity with human hepatic C-S lyase activity and a physiological role for this enzyme |
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Authors: | Lorraine D. Buckberry Ian S. Blagbrough Barrie W. Bycroft P.Nicholas Shaw |
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Affiliation: | Department of Pharmaceutical Sciences, University of Nottingham, UK. |
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Abstract: | The C-S lyase enzymes are responsible for the generation of mutagenic and cytotoxic metabolites via aberrant drug-metabolising pathways in mammalian tissues. We have examined human hepatic cytosolic, mitochondrial and microsomal fractions for evidence of C-S lyase activity. The cytosolic enzyme was purified using fast protein liquid chromatography over FFQ Sepharose, Mono P and Superose 12. An homogeneous protein (monitored by SDS-PAGE) was obtained following purification, and an 11-fold increase in C-S lyase specific activity was observed. The molecular weight of the enzyme was found to be 37 kDa in denaturing conditions, 82.3 kDa in non-denaturing conditions, and the C-S lyase activity was shown to co-purify with kynurenine aminotransferase activity when the transaminase activity of the enzyme was examined with kynurenine as the substrate. |
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Keywords: | Cysteine conjugate β -lyase C-S lyase Kynurenine aminotransferase Human hepatic tissue S-(E-1,2-Dichlorovinyl)-l-cysteine DCVC |
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